@article{GDZPPN002416107, title = {Eigenvalue Comparison Theorems and Its Geometric Applications.}, journal = {Mathematische Zeitschrift}, volume = {142}, year = {1975}, pages = {289-297}, zbl = {0329.53035}, url = {http://dml.mathdoc.fr/item/GDZPPN002416107} }
Cheng, Shiu-Yuen. Eigenvalue Comparison Theorems and Its Geometric Applications.. Mathematische Zeitschrift, Tome 142 (1975) pp. 289-297. http://gdmltest.u-ga.fr/item/GDZPPN002416107/